The ShadowMusic Web Community

Has anyone got one of these? I've used it a lot for several years but one of the channel select buttons (which is the route to EQ etc.) has ceased to operate. I wonder if I've done something in error to cause this. Visiting Tascam forums is a nightmare and so far hasn't provided any result. Otherwise, the unit is working perfectly but I accept it may be wear and tear that's behind it.
rjw